Pressure fluid operated motor

ABSTRACT

The present invention is an air motor adapted especially for use in propelling automobiles. It includes a rotor having a plurality of circumferentially arranged pressure chambers closed on all sides and bottom but open at the rotor periphery. A stationary housing at least partially encloses the rotor, the latter being rotatably mounted therein. The housing includes a cylindrical shroud which completes the closure of said chambers at the rotor periphery. The chambers are arranged in laterally adjacent pairs, each chamber being of triangular shape. There are a plurality of said pairs circumferentially contiguously arranged around the entire rotor. Means are provided for introducing and exhausting pressure fluid selectively to and from said chambers. One circumferential series of said chambers, consisting of one chamber of each pair, serve in propelling the rotor in one direction and the remaining chambers serving as a second series to propel the rotor in the opposite direction. The means for introducing and exhausting pressure fluid to and from said chambers, respectively, are in the form of passages in the housing shroud, these passages being equally spaced circumferentially about the shroud with the exhaust passage being alternated with the inlet passages. The spacing between adjacent inlet and exhaust passages is such that as pressure fluid is being introduced into one chamber, pressure fluid from an adjacent chamber is being exhausted. Circumferentially adjacent chambers are separated by radially disposed walls which serve as impellers and over which a pressure differential can be created for causing movement of the rotor in a predetermined direction. The chambers and air passages communicating therewith are so constructed as to conserve pressure fluid in the development of the rotational forces.

United States Patent Robert G. Bandy 10206 Lima Road, Fort Wayne, lad. 46808 [21] Appl. No. 883,812

[22] Filed Dec. 10,1969

[45] Patented July I3, 197] [72} Inventor [54] PRESSURE FLUID OPERATED MOTOR Primary Examinr-Henry F. Raduazo Arrorneyl-lood, Gust, lrish dtlundy ABSTRACT: The present invention is an air motor adapted especially for use in propelling automobiles. It includes a rotor having a plurality of circumferentially arranged pressure chambers closed on all sides and bottom but open at the rotor periphery. A stationary housing at least partially encloses the rotor, the latter being rotatably mounted therein. The housing includes a cylindrical shroud which completes the closure of said chambers at the rotor periphery. The chambers are arranged in laterally adjacent pairs, each chamber being of triangular shape. There are a plurality of said pairs circumferentially contiguously arranged around the entire rotor. Means are provided for introducing and exhausting pressure fluid selectively to and from said chambers. One circumferential series of said chambers, consisting of one chamber of each pair, serve in propelling the rotor in one direction and the remaining chambers serving as a second series to propel the rotor in the opposite direction.

The means for introducing and exhausting pressure fluid to and from said chambers, respectively, are in the form of passages in the housing shroud, these passages being equally spaced circumferentially about the shroud with the exhaust passage being alternated with the inlet passages. The spacing between adjacent inlet and exhaust passages is such that as pressure fluid is being introduced into one chamber, pressure fluid from an adjacent chamber is being exhausted. Circumferentially adjacent chambers are separated by radially disposed walls which serve as impellers and over which a pressure differential can be created for causing movement of the rotor in a predetermined direction.

The chambers and air passages communicating therewith are so constructed as to conserve pressure fluid in the development of the rotational forces.

PATENIEI) JUL 1 3 I9?! SHEEI 1 OF 5 IN VENTOE: ROBERT G,EANDYI Arromwvs,

PATENIEnJuuamn 3,592,558

SHEET 2 0F 5 Ill/Il INVENTOR. EosEE-T G. SANDY,

7 la BY 94 ATTQFPNEYS- PATENIEflJuuwn 3.592558 saw u 0F 5 95 FIGJO INVENTQR: ER G. BANDY,

BY W,WIQML* ATTORNE'YQ.

PRESSURE FLUID OPERATED MOTOR FIELD OF THE INVENTION The present invention relates generally to motors of the fluid-actuated type and more particularly to an air motor suitable for use in propelling an automobile.

DESCRIPTION OF THE PRIOR ART In the prior art, there is known an air motor construction which includes a housing and a rotor rotatable therein, inlet jets mounted in the housing being directed against impeller blades on the periphery of the rotor and the air under pressure entrapped in the rotor chambers being exhausted through other ports in the housing circumferentially removed from the inlet jets. The spacing between the inlet ducts and exhaust ports is such that several impeller blades on the rotor are disposed therebetween and further the exhausted air is completely spent without any attempt being made to recycle or reuse a portion thereof. Further than this, the impeller blades on the rotor are so constructed that the rotor can be driven only in a single direction.

SUMMARY OF THE INVENTION In accordance with the broader aspects of this invention there is provided an air motor which includes a rotor having a plurality of circumferentially arranged pressure chambers closed on all sides and bottom but open at the rotor periphery. A stationary housing at least partially encloses the rotor and includes a cylindrically shaped shroud which completes the closure ofthe rotor chambers at the periphery thereof. Means are provided for introducing a fluid under pressure to predetermined ones of said chambers and other means are provided for exhausting pressure fluid from other of said chambers. Each of the chambers includes a wall which separates one chamber which is being pressurized from another one that is being exhausted.

It is an object of this invention to provide a motor operated by pressure fluid which is compact, light in weight, and of durable construction.

It is another object of this invention to provide an air motor particularly adapted for use in propelling an automotive vehicle.

It is still another object of this invention to provide an air motor so constructed that a common rotor can be selectively driven in opposite directions through the intermediary of particularly arranged impeller devices on the rotor.

It is yet another object of this invention to provide an air motor wherein a portion of the air being exhausted may be utilized for partially pressurizing a particular chamber just prior to the application of full operating pressure whereby at least a portion of the pressurized air is conserved for producing useful work.

DESCRIPTION OF THE DRAWINGS The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. I is a partial axial section ofone embodiment of this in vention;

FIG. 2 is a fragmentary side view thereof developed into a flat plane and partially broken away for clarity of illustration;

FIG. 3 is a cross section taken substantially along section line 33 of FIG. 1.

FIG. 4 is a partial perspective view, broken away in part, of the stator and rotor portions of the embodiment of FIG. I;

FIGS. 5 and 6 are part-sectional views taken substantially along section line 5, 6-5, 6 of FIG. I showing different relative positions ofthe rotor with respect to the stator;

FIG. 7 is a fragmentary sectional view taken substantially along section line 7-7 of FIG. 1;

FIG. 8 is a top plan view of one of the elements used in forming the multiple chambers of the rotor;

FIG. 9 is a side view thereof with a second such element shown in phantom in assembly therewith;

FIG. I0 is a side view ofa partition element used in forming the forward and reverse chambers in the rotor;

FIG. I] is a perspective illustration showing a series of the elements of FIGS, 8 and I0 assembled together in forming a portion of the rotor;

FIG. I2 is a cross section similar to FIG. 3 of a second embodiment of this invention;

FIG. 13 is a fragmentary side view like FIG. 2 developed into a flat plane of the embodiment of FIG. 12; and

FIG. 14 is a perspective illustration like FIG. ll showing some of the elements of the embodiment of FIG. 12 assembled together and forming a portion of the rotor.

Referring to the drawings, and more particularly to FIG. I, the air motor of this invention is shown as being mounted on the left front axle It) ofa conventional automobile. Four such air motors may be used on such a vehicle, one being secured to each wheel, as will become apparent from the description that follows.

The axle 10 which is stationary is secured to a support 12 on the vehicle forming a conventional part of the steering mechanism. Mounted on the axle 10 is a cylindrically shaped motor housing generally indicated by the numeral 14 consisting of a stationary backing plate 16 and a cylindrically shaped coaxial shroud 18. The backing plate 16 is secured to the part 12 by means of three bolts 20 triangularly arranged.

The shroud I8 includes a cylindrical body 22 of some thickness as shown in FIG. I which is provided with two peripheral air ducts 24, 26 positioned as shown and several part-annular ducts as indicated by the numerals 28 and 30. The ducts 24 and 26, for all practical purposes, completely encircle the body 22 but are interrupted or closed by a section 32 as shown more clearly in FIGS. 3 and 7. This integral section 32 is disposed between two conduit fittings 34, 36 which communicate, respectively, with the ducts 26, 24. The reason for providing the section 32 is to facilitate positioning of the nipples 34, 36 on the back side of plate 16 for connection to the ducts 24 and 26.

Referring to FIGS. I and 3, the ducts 24, 26, 28, 30 are closed by means of a steel or the like cylindrical sleeve 38 hermetically secured to the body 22 as shown.

Still referring to the construction of the housing I4 and in particular to the ducts, a series of inlet ports or passages indicated by the numeral 40 with a suffix letter penetrate the inner wall of the body 22 to communicate with the passage 26. All of these passages 40 which are equally spaced apart are of cylindrical shape on axes tangent to a common circle coaxial with the axle 10. These passages 40 are of such size and shape as to correspond to nozzles capable of forming pressure fluid passing therethrough into jets which can impulse a blade or wall on the rotor to be described hereinafter. In the embodiment illustrated, the passages 40 are elongated holes drilled at the angles shown.

A second series of similar passages 42 are likewise drilled in the body 22 to communicate with the passage 24, the axes of these passages lying on tangents to an imaginary cylindrical surface which includes the circle of tangency of the passages 40. As shown in FIG. 3, the passages 42 are also equally spaced, being the same in number as the passages 40.

Several exhaust ports are drilled radially through the shroud I8, these being indicated by the numeral 44 with a suffix letter. These exhaust ports 44 are equally spaced apart and are interposed between adjacent inlet ports 40, 42, as shown. More particularly, these exhaust ports are spaced from the inlet ports 40 by a distance corresponding to the dimension b in FIG. 3 for a purpose which will be explained hereinafter. The relative spacing between all of the ports and the remainder of the mechanism is substantially to scale as shown in FIGS. 1 and 3.

in FIG. I, the ports 40 and 42 are laterally spaced in registry with ducts 24 and 26, respectively.

The ducts 28 and 30 previously mentioned in FIG. 1 are shown in greater detail in FIGS. 4, and 6. There are several ducts as indicated by the suffix letters arranged in a common imaginary circle which are part annular. each having end passages denoted by the numeral 46 with letter suffixes which pass through to the interior ofthe shroud 18. As clearly shown in FIGS. 5 and 6. each of the ducts 30 spans substantially between adjacent exhaust ports 44, the spacing between these exhaust ports and the duct ends 46 being critical as will later be explained. The location of these ducts 30 and the ends 46 are drawn substantially to scale in FIGS. 5 and 6.

Referring once again to FIG. 1, it should be noted that there are an equal number of part-annular ducts 28 as ducts 30.

The rotor construction will now be described. The rotor is generally indicated by the numeral 48 and is generally cylindrical in shape. It is provided with a hub 50 journaled on the axle 10, a central supporting disc 52 having a series of circularly arranged bolts or studs 54 for mounting an automobile wheel, a brake drum 56 of conventional configuration to be used basically as an emergency brake, and two annular sideplates S8, 60 which are coaxially secured to the drum 52 as shown. A relatively thin metal sleeve 62 surrounding and secured to the brake drum 56 is securely fitted to the inner peripheral edges of the sides 58, 60. The side 58 is disposed adjacent to with slight clearance the backing plate 16 of the housing, the outer periphery being coextensive, with slight clearance. with the inner surface ofthe shroud IS.

A series of circumferentially arranged pressure chambers are formed between the sides 58, 60, these chambers being in pairs of identical construction whereby a description of one pair will suffice for all. Referring in particular to FIGS. 3 through 6 and 8 through 11, a chamber 64 is defined in part by an element 80 (FIG. 8) composed ofa radially extending wall 66,21 curved bottom 68, and a right angle flange 70. The wall 66 extends radially between the cylindrical sleeve 62 and the inner surface of the shroud l8 and axially between the two sides 58 and 60 to which it is hermetically secured as by weld ing or the like. The flange 70 conforms substantially to the curvature of the inner surface of the shroud [8, having slight clearance therewith. As shown clearly in FIGS. 3,5 and 6, the bottom 68 is convexly curved radially outwardly and extends from the inner sleeve 62 to a position adjacent to the rotor periphery.

Laterally adjacent to the chamber 64 is a second chamber 72 defined in part by an element 82 (like element 80) composed ofa curved bottom plate 74, a radial wall 76, and an inturned flange 78, these parts occupying the same position in the rotor as those defining the chamber 64 but in reverse. For example, as seen more clearly in FIG. 3, the two radial walls 66 and 76 are circumferentially spaced apart and facing each other. The two right-angle flanges 70 and 78 are directed toward each other as shown. The two curved bottoms 68 and 74 extend oppositely in crossing relation. This is further explained in connection with FIGS. 8 through ll. Each of the elements 80 and 82 are shaped as shown in FIG. 8 with the bottoms 68 and 74 being essentially triangular. The diagonal edges of these two parts indicated by the numerals 84 and 86, respectively, are adjacent to each other at the crossover point 87 (FIGS. 3 and 11 and otherwise are essentially coplanar as viewed in side elevation (see FIG. 2). The apices of the two bottom parts 68 and 74 terminate adjacent to the flanges 70 and 78 and are there welded. A flat partition 88 is shaped sub stantially as shown in FIG. 10. This partition 88 is welded along the curved bottom edge 89 to the edges 84 and 86 (FIG. I] such that the curved outer edge 90 substantially coincides with the cylindrical exterior of the rotor itself. Each of the chambers 64 and 72, therefore, are defined by the two preformed elements 80 and 82 (FIG. I I l and the partition 88, the two bottoms 68 and 74 being curved oppositely as shown. As shown in FIG. 2, these chambers are substantially triangular in shape.

As shown more clearly Again referring to FIG. 1], all of the various chambers in the assembly are constructed as just described, the end walls like walls 66 and 76 being abutted together as shown. The right-angle flanges like flanges 70 and 78 of abutting walls like 66 or 76 extend oppositely, thereby forming a platelike member denoted by the numeral 92 which serves as a valve element. The opposite edges of the valve element 92 are, in the illustrated embodiment, provided with angular grooves 94 and Q6 which precisely align with the respective inlet ports 40 and 42 as shown in FIGS. I and 3. However, these grooves 94 and 96 may be omitted as explained later. These valve elements 92 have close-fitting clearances with the inner surface of the shroud l8 and are of such size that they control the opening and closing in proper relation ofall of the ports 40, 42 and 44.

The circumferential spacing between the walls 66, 76 ofthe various chambers is made equal, as is the spacing between all of the other corresponding parts, as shown substantially to scale in FIGS. 3, 5 and 6. Corresponding edges of the valve element 92 are circumferentially spaced apart by a distance denoted by the letter a (FIG. 3) which is greater than the dimension b which is between centers of ports 40a and 44a.

A conventional brake mechanism of the T-section shoe type, indicated by the numeral 98, is operatively mounted inside the drum S6 for coaction therewith, the two brakeshoes being anchored conventionally to the backing plate 16 (FIG. I).

In operation, air under pressure admitted to the fitting 34 enters the annular duct 26. From the duct 26 it passes through the inlet ports 50 into various chambers of the rotor. Referring, for example, to FIG. 3, air entering the inlet port 400 at high pressure is formed into a jet which impinges the chamber wall 100. Air passing through the inlet port 40b impinges the wall I02, air through the chamber 40c impinges wall 104, air through the port 40d impinges the wall 106, and so on. Those chambers on the opposite sides of the walls I00, 102, 104 and 108 are exhausted to the atmosphere via the respective exhaust ports 44a, 44b, 44c and 44e which results in a pressure differential being developed over these walls which propels the rotor counterclockwise. It will be noted that the impulse of the air jets against the respective chamber walls provides a force tending to rotate the rotor counterclockwise also. Thus, the conjoint action of two different forces, one the impulse and the other the differential pressure, tend to rotate the re tor.

If it is desired to turn the rotor in reverse, it is only necessary to shut off the air communicating with the fitting 34 (FIG. 7) and couple the air pressure to the fitting 36 which communicates with the annular duct 24. This couples the air to the reverse inlet ports 42 which act against the opposite sides of the chamber walls, thereby driving the rotor oppositely.

It will be noted that the full area of each wall through 108 is available for receiving the jet blast as well as for developing the differential pressure thereover. By reason of the chamber bottoms being curved convexly outwardly as shown, the chamber volumes are minimized, thereby reducing the quantity of air required for producing the rotational forces. The diagonal partitions 88 which separate the laterally adjacent chambers are important for the reason that they maintain the wall area at a maximum yet contribute to reducing the volume of the chambers. Thus. maximum rotational force is achieved with minimum chamber volume. This contributes to greater efficiencies inasmuch as the quantity of air required for develr ping the force is kept to a minimum.

Referring to FIGS 5 and 6, the purpose of the part-annular ducts 28 and 30 will be explained. It is assumed that the rotor is rotating counterclockwise. In FIG. 6, it will be noted that the chamber 64 is at the particular moment about to be exhausted, port 440 being closed. The duct 300, however, is in communication with the chamber 64 via its passage 46a. Pressure fluid in the chamber 64 is thereby conducted via the duct 30c to the adjoining chamber 110. The valve element 920 at this particular moment has the inlet port 400 closed, such that the chamber 110, which just moments before was exhausted to atmosphere, is now being pressurized from chamber 64. As the rotor continues its counterclockwise movement, the valve element 92b will close off the passage 46c and prevent further communication between the two chambers 64 and 110 and the valve element 921: will open exhaust port 44a. The valve 92a will uncover the port 400 thereby permitting the chamber I to be further pressurized, thereby developing the rotational forces already described. The purpose of the part-annular ducts 28, 30 now apparent is to prepressurize or prime previously exhausted chambers just instants before full pressurization thereof. Thus, while a substantial portion of the air used in pressurizing the chambers is exhausted to atmosphere via the exhaust ports 44, still a part of the used air is coupled back to an exhausted chamber for partially pressurizing the same just ahead of full pressurization thereof. This provides a saving in the amount of air used in producing rotor rotation.

A second embodiment of this invention is shown in FIGS.

I2, I3 and I4. Like parts are identified by like numerals in the 100 series. For example, the part 440 in FIGS. 5 and 6 correspond to the numeral 1440 in FIGS. 12, I3 and I4, and so FIG. 12 is substantially to scale. The duct I30c in FIG. I2 corresponds to the duct 30c in FIGS. 5 and 6, but as shown, it is substantially shorter. The exhaust duct 1440 is located intermediate the opposite ends of the duct 1300 as shown. There are five inlet ports 140a circumferentially spaced apart as shown, not all of these being numbered. There are five exhaust ports 1440, only one of these bearing a numeral. In all essential details, the configuration of this second embodiment of FIG. 12 is like that of the first embodiment of the preceding figures. In those details where there are differences, additional description is given. For example, the chamber floor I68 which corresponds to the floor 68 in the preceding figures is planar as shown. The valves 1920, 192b, I920, etc. corresponding to the valves 92a, 92b, 92c, etc. are constructed slightly differently as will now be explained. For this purpose, reference is made to FIGS. 13 and I4.

FIG. I3 is a side view of the rotor I62 developed into a flat plane. The valves I92 are each composed of circumferentially extending flanges I70 and I78, each valve I92 having one flange I70 and another oppositely extending flange 178. The flanges I70, 178 are essentially flat plates with outer surfaces curved to conformto that of the inner surface of the stator and are edge welded or otherwise secured to the radially outer extremity of the chamber wall 166. The two flanges 170, I78 are identical in size and construction and extend axially of the rotor for a distance shorter than the rotor width.

The partition 188 in this embodiment corresponding to the partition 88 in the preceding figures has the opposite edge portions I89 and It bent over at obtuse angles such that the edges I93 and 195 lie in the circumferential surface defined by the flanges I70 and 178. The bent portions 189 and I91 provide clearance for communication between the two chambers I64 and 172 with the respective inlet ports 140 (not shown in FIG. [3).

ln explaining the operation of the embodiment of FIGS. I2, 13 and 14, it is assumed that the rotor 162 is rotating counterclockwise. At the particular moment, the chamber I65 is being pressurized from the inlet port 140a, and the chamber 164 is being exhausted via the exhaust port I44a. Both ends of the duct 130C are in communication with the chamber I64.

When the rotor has moved a short distance to the point at which the flange 170 of chamber I65 closes exhaust port 1440 and otherwise is perfectly centered between the ends of the duct 1311c. the latter communicates with the two chambers I64 and I65. The chamber 164 previously exhausted now receives a flow of air from the pressurized chamber I65 thereby prepressurizing chamber I64. The flange I70 of chamber I67 at this point closes inlet port I400. Further movement of the rotor 162 a distance equal to about the diameter of the duct 1306 results in the flange I70 closing communication of duct 130C with chamber 164. Additional rotation for about the same distance will result in the inlet port I40b communicating with the chamber 164 for pressurizing the latter. As the rotor continues the flange 170 of chamber 165 will uncover exhaust port 144 thereby exhausting chamber I65.

Prepressurization is accomplished by means of the ducts c which, as compared with the ducts 30c of the first embodiment (FIGS. 5 and 6) are much shorter thereby providing quicker and more efficient communication of air from the pressurized to the exhausted chambers. It will be noted that the flow of prepressurization is in the direction of rotor travel and is so timed that a chamber will be prepressurized just instants before the inlet port communicates with the prepressurized chamber.

It will be understood, of course, that there are a multiplicity of ducts I300 spaced around the circumference of the stator with the respective exhaust port being located intermediate the ends thereof as already explained.

Other embodiments of this invention will appear as obvious to a person skilled in the art and it is intended that these shall be covered herein so long as they do not violate the scope of the appended claims.

What I claim is:

1. An air motor comprising a rotor having a plurality of circumferentially arranged pressure chambers closed on all sides and bottom but open at the rotor periphery, a stationary housing at least partially enclosing said rotor, means mounting said rotor for rotation within said housing, said housing including a shroud which completes the closure of said chambers at said rotor periphery, means for introducing a fluid under pressure to predetermined ones of said chambers. means for exhausting pressure fluid from other of said chambers, said chambers each including a wall which separates a chamber which is being pressurized from one that is being exhausted.

2. The air motor of claim I including means for communicating at least a part of the pressure fluid exhausted from one chamber for prepressurizing another chamber, and valve means for preventing communication of pressure fluid to or the exhausting of pressure fluid from said other chamber during prepressurizing thereof.

3. The air motor of claim I including valve means for controlling the communication of pressure fluid to and from said chambers in a pattern in which chambers undergoing exhausting are separated from chambers being pressurized.

4. The air motor of claim 3 in which said introducing and exhausting means include a plurality of inlet and exhaust ports, respectively, in said housing circumferentially spaced apart and communicating with said chambers, respectively, said valve means including elements on said rotor cooperatively disposed to open and close alternately said ports as said rotor rotates, said ports being equally spaced apart, said valve elements being equally spaced apart, the spacing between said valve elements being greater than the spacing between adjacent ports. said inlet and outlet ports being alternated about the circumference of said rotor, the spacing between said ports and said elements further being such that two peripherally adjacent valve elements can register with the close peripherally adjacent inlet and exhaust ports.

5. The air motor of claim 4 in which said walls extend radially and said inlet ports are elongated jetlike passages in said shroud arranged parallel to respective chords of the rotor and angled toward said walls, respectively, whereby pressure fluid in jet form may be directed against said walls.

6. The air motor of claim 5 in which said shroud has a coaxial annular duct therein in communication with said inlet ports, said chambers each being defined by a bottom which inclines radially outwardly from the radially inner portion of the wall thereof to a point adjacent to a valve element at the rotor periphery, said bottom extending generally circumferential of said rotor and presenting a surface exposed radially outwardly, each said valve element being in the form of a flange on the outer radial portion of a chamber wall which extends circumferentially of said rotor, said shroud having a cylindrical inner surface coaxial and contiguous with the periphery of said rotor, said inlet and exhaust ports opening through said inner shroud surface, said valve elements being disposed contiguous to said inner shroud surface in registry with said ports for controlling the opening and closing of the latter.

7, The air motor of claim 6 in which there is a second chamber beside each firsbmentioned chamber, each second chamber having a bottom like the bottom of said first-mentioned chamber but inclines oppositely in extending from the radially inner portion of one wall to a valve element at the periphery of the rotor, a

equally in said shroud, the second inlet ports being disposed substantially laterally adjacent to the first inlet ports and angled oppositely, said first and second inlet ports being in lateral registry with said first and second chambers, and a second annular air duct in said housing in communication with said second inlet ports.

8. The air motor of claim 7 in which the space between circumferentially adjacent walls in substantially rectangular, said partition extending substantially diagonally across the space thereby forming said first and second chambers into triangular shapes, and said bottoms being convexly curved radially outwardlyl 9. The air motor of claim 8 in which said first and second inlet ports are aligned with the apices of the first and second chambers, respectively, said first chambers being of equal size and shape and arranged in a connected circumferential series, said second chambers being of equal size and shape and also arranged in a connected circumferential series, both first and second chambers being symmetrically arranged about the axis of said rotor with the first chambers being reversed in position with respect to said first chambers whereby said first chambers may be utilized for forward rotation of said rotor and said second chambers for reverse and brakingv 10. The air motor ofclaim 9 in which a brake drum is coaxially disposed within and rotatable with said rotor, and brake shoes mounted within said drum for operative engagement therewith.

11. The air motor of claim 6 in which there is at least one prepressurizing duct in said shroud extending circumferentially thereof, said duct having opposite ends spaced shroud opening through the 12 The air motor of claim I] in which said prepressurizing duct is longer than the chamber dimension which extends circumferentially of said shroud, the last-mentioned inlet port being disposed intermediate the duct ends, and the lasbmentioned exhaust port being closeiy adjacent to one duct end so that both the exhaust port and duct end may be closed simultaneously by a valve element.

13. The air motor of claim 11 in which the prepressurizing duct is shorter than the circumferential dimension of a chamber, the last-mentioned exhaust port being disposed intermediate said duct ends and close enough thereto to have one duct end and the exhaust port closed simultaneously by a valve element.

14. The air motor of claim 13 in which there are a plurality of said prepressurizing ducts spaced circumferentially of said shroud, each such duct having associated therewith respective inlet and exhaust ports as aforedescribedi 

1. An air motor comprising a rotor having a plurality of circumferentially arranged pressure chambers closed on all sides and bottom but open at the rotor periphery, a stationary housing at least partially enclosing said rotor, means mounting said rotor for rotation within said housing, said housing including a shroud which completes the closure of said chambers at said rotor periphery, means for introducing a fluid under pressure to predetermined ones of said chambers, means for exhausting pressure fluid from other of said chambers, said chambers each including a wall which separates a chamber which is being pressurized from one that is being exhausted.
 2. The air motor of claim 1 including means for communicating at least a part of the pressure fluid exhausted from one chamber for prepressurizing another chamber, and valve means for preventing communication of pressure fluid to or the exhausting of pressure fluid from said other chamber during prepressurizing thereof.
 3. The air motor of claim 1 including valve means for controlling the communication of pressure fluid to and from said chambers in a pattern in which chambers undergoing exhausting are separated from chambers being pressurized.
 4. The air motor of claim 3 in which said introducing and exhausting means include a plurality of inlet and exhaust ports, respectively, in said housing circumferentially spaced apart and communicating with said chambers, respectively, said valve means including elements on said rotor cooperatively disposed to open and close alternately said ports as said rotor rotates, said ports being equally spaced apart, said valve elements being equally spaced apart, the spacing between said valve elements being greater than the spacing between adjacent ports, said inlet and outlet ports being alternated about the circumference of said rotor, the spacing between said ports and said elements further being such that two peripherally adjacent valve elements can register with the close peripherally adjacent inlet and exhaust ports.
 5. The air motor of claim 4 in which said walls extend radially and said inlet ports are elongated jetlike passages in said shroud arranged parallel to respective chords of the rotor and angled toward said walls, respectively, whereby pressure fluid in jet form may be directed against said walls.
 6. The air motor of claim 5 in which said shroud has a coaxial annular duct therein in communication with said inlet ports, said chambers each being defined by a bottom which inclines radially outwardly from the radially inner portion of the wall thereof to a point adjacent to a valve element at the rotor periphery, said bottom extending generally circumferential of said rotor and presenting a surface exposed radially outwardly, each said valve element being in the form of a flange on the outer radial portion of a chamber wall which extends circumferentially of said rotor, said shroud having a cylindrical inner surface coaxial and contiguous with the periphery of said rotor, said inlet and exhaust ports opening through said inner shroud surface, said valve elements being disposed contiguous to said inner shroud surface in registry with said ports for controlling the opening and closing of the latter. 7, The air motor of claim 6 in which there is a second chamber beside each first-mentioned chamber, each second chamber having a bottom like the bottom of said first-mentioned chamber but inclines oppositely in extEnding from the radially inner portion of one wall to a valve element at the periphery of the rotor, a partition separating the first and second chambers, said partition extending circumferentially arranged inlet ports like the first-mentioned inlet ports spaced equally in said shroud, the second inlet ports being disposed substantially laterally adjacent to the first inlet ports and angled oppositely, said first and second inlet ports being in lateral registry with said first and second chambers, and a second annular air duct in said housing in communication with said second inlet ports.
 8. The air motor of claim 7 in which the space between circumferentially adjacent walls in substantially rectangular, said partition extending substantially diagonally across the space thereby forming said first and second chambers into triangular shapes, and said bottoms being convexly curved radially outwardly.
 9. The air motor of claim 8 in which said first and second inlet ports are aligned with the apices of the first and second chambers, respectively, said first chambers being of equal size and shape and arranged in a connected circumferential series, said second chambers being of equal size and shape and also arranged in a connected circumferential series, both first and second chambers being symmetrically arranged about the axis of said rotor with the first chambers being reversed in position with respect to said first chambers whereby said first chambers may be utilized for forward rotation of said rotor and said second chambers for reverse and braking.
 10. The air motor of claim 9 in which a brake drum is coaxially disposed within and rotatable with said rotor, and brake shoes mounted within said drum for operative engagement therewith.
 11. The air motor of claim 6 in which there is at least one prepressurizing duct in said shroud extending circumferentially thereof, said duct having opposite ends spaced apart circumferentially of said shroud opening through the shroud surface in communication with said chambers, the distance between said duct ends being such that they communicate with two different chambers simultaneously during a portion of the rotation of said rotor, said duct ends being so positioned with respect to the inlet and exhaust ports that communication between said two different chambers via said prepressurizing duct occurs following communication of one chamber thereof with one inlet port and the other chamber thereof with an exhaust port and also following closure of these last-mentioned inlet and exhaust ports by respective ones of said valve elements.
 12. The air motor of claim 11 in which said prepressurizing duct is longer than the chamber dimension which extends circumferentially of said shroud, the last-mentioned inlet port being disposed intermediate the duct ends, and the last-mentioned exhaust port being closely adjacent to one duct end so that both the exhaust port and duct end may be closed simultaneously by a valve element.
 13. The air motor of claim 11 in which the prepressurizing duct is shorter than the circumferential dimension of a chamber, the last-mentioned exhaust port being disposed intermediate said duct ends and close enough thereto to have one duct end and the exhaust port closed simultaneously by a valve element.
 14. The air motor of claim 13 in which there are a plurality of said prepressurizing ducts spaced circumferentially of said shroud, each such duct having associated therewith respective inlet and exhaust ports as aforedescribed. 